Headlamp Unit - Jeep KJ 2005 Service Manual

8L - 40 LAMPS/LIGHTING - EXTERIOR
HEADLAMP LOW BEAM RELAY
DESCRIPTION
Fig. 33 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
The headlamp low beam relay is a conventional
International Standards Organization (ISO) micro
relay (Fig. 33). Relays conforming to the ISO specifi-
cations have common physical dimensions, current
capacities, terminal patterns, and terminal functions.
This relay is contained within a small, rectangular,
molded plastic housing and is connected to all of the
required inputs and outputs through five integral
male spade-type terminals that extend from the relay
base plate.
The headlamp low beam relay is located in the
Junction Block (JB) on the driver side instrument
panel end bracket. The headlamp low beam relay
cannot be adjusted or repaired and, if faulty or dam-
aged, it must be replaced with a new unit.
OPERATION
The headlamp low beam relay is an electromechan-
ical switch that uses a low current input from the
Body Control Module (BCM) to control a high current
output to the headlamp low beam filaments. Within
the relay are an electromagnetic coil, a movable con-
tact and two fixed contact points. A resistor is con-
nected in parallel with the coil, and helps to dissipate
voltage spikes and electromagnetic interference that
can be generated as the field of the relay coil col-
lapses.
The movable common supply contact point is held
against the fixed normally closed contact point by
spring pressure. When the relay coil is energized, an
electromagnetic field is produced by the coil wind-
ings. This field draws the movable contact point
away from the normally closed contact, and holds it
against the normally open contact. When the relay
coil is de-energized, spring pressure returns the mov-
able contact back against the normally closed con-
tact.
The inputs and outputs of the headlamp low beam
relay include:
• Common Supply Terminal (30) - The common
feed terminal is connected to a fused B(+) circuit at
all times.
• Coil Ground Terminal (85) - The common feed
terminal is connected to a fused B(+) circuit at all
times.
• Coil Battery Terminal (86) - The coil battery
terminal is connected to a control output of the Body
Control Module (BCM) through a low beam relay
control circuit. The BCM controls headlamp low
beam operation by controlling a ground path through
this circuit.
• Normally Open Terminal (87) - The normally
open terminal is connected to the headlamp low
beam filaments through the low beam relay output
circuit and provides battery voltage to the headlamp
low beams whenever the relay is energized.
• Normally Closed Terminal (87A) - The nor-
mally closed terminal is not connected in this appli-
cation, but will have
whenever the relay is de-energized.
The headlamp low beam relay can be diagnosed
using conventional diagnostic tools and methods.
Refer to the appropriate wiring information.

HEADLAMP UNIT

REMOVAL
LAMP
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the grille panel from the grille opening
reinforcement. (Refer to 23 - BODY/EXTERIOR/
GRILLE - REMOVAL).
(3) Remove the two screws that secure the mount-
ing tabs on the inboard side of the headlamp unit
housing to the grille opening reinforcement (Fig. 34).
(4) Pull the inboard side of the headlamp unit
away from the grille opening reinforcement far
enough to disengage the locator tab on the outboard
side of the unit (Fig. 35) or (Fig. 36) from the engage-
ment slot in the outboard edge of the reinforcement.
(5) Pull the headlamp unit away from the grille
opening reinforcement far enough to disconnect the
wire harness connectors from the headlamp bulb
battery voltage present
KJ